CN1968241A - Distributed MIMO system and channel estimation method - Google Patents

Distributed MIMO system and channel estimation method Download PDF

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CN1968241A
CN1968241A CN 200610035731 CN200610035731A CN1968241A CN 1968241 A CN1968241 A CN 1968241A CN 200610035731 CN200610035731 CN 200610035731 CN 200610035731 A CN200610035731 A CN 200610035731A CN 1968241 A CN1968241 A CN 1968241A
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data
module
pilot
frequency sequence
pilot frequency
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孔婷
唐友喜
邵士海
李�杰
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Huawei Technologies Co Ltd
University of Electronic Science and Technology of China
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Huawei Technologies Co Ltd
University of Electronic Science and Technology of China
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Abstract

The invention relates to a distribution multi-input multi-output (MIMO) system and relative channel evaluate method, wherein said system comprises sender and receiver; the sender comprises distribution MIMO code module, and multiply parallel sending circuits for inserting pilot sequence and adding protective distance into dataflow output from coding module, to form and send data frame; the receiver comprises multiply parallel receiving circuits for receiving the data frame, obtaining the pilot sequence and data section from the data frame; the pilot mark module for outputting the number of sending circuit and the pilot sequence at preset length; channel evaluating module for obtaining channel evaluating matrix via the pilot sequence of receiving circuit and the pilot sequence of pilot mark module. The invention can process channel evaluation of distribution MIMO system.

Description

Distributed MIMO system and channel estimation methods
Technical field
The present invention relates to the technical field of data processing in the radio communication, especially relate to a kind of distributed MIMO system and channel estimation methods.
Background technology
In recent years, distributed antenna system (Distributed Antenna System is called for short DAS) receives increasing concern as a kind of new trend of following public wireless network access.As shown in Figure 1, distributing antenna system is antenna sets (antenna sets is that a plurality of antennas 100 are connected in base station 120 formations) process optical fiber or the cable and travelling carriage (center signal processor) 130 communication systems that link to each other that will be in diverse geographic location.Because the distribution of antenna on diverse geographic location, distributed antenna system can provide grand diversity, reach higher power system capacity, effectively shorten the access distance of signal, the power requirement of reduction to transmitting improves cell coverage, therefore, distributing antenna system is used to solve the covering problem of indoor wireless communication at first, progressively is applied in the cdma system then.
As everyone knows, multiple-input and multiple-output (Multi-Input Multi-Output, the be called for short MIMO) communication technology is one of key technology of new generation of wireless communication system, and it has good spectrum efficiency, higher system capacity and communication quality preferably.The MIMO communication means adopts the Space Time Coding technology, the empty time-code that uses in this technology mainly comprises following two big classes: a class is based on space-time trellis codes (the SpaceTime Trellis Codes of transmit diversity, be called for short STTC) and Space-Time Block Coding (Space Time Block Codes is called for short STBC); The another kind of hierarchical space-time code (Layered Space TimeCodes is called for short LSTC) that is based on non-transmit diversity.
Space-time trellis codes is a kind of design of taking all factors into consideration chnnel coding, modulation, transmit diversity and receive diversity, and the coded system of bigger coding gain, the availability of frequency spectrum and diversity gain can be provided.The performance of space-time trellis codes is fine, but its complexity of decoding is quite high.Particularly, when number of transmit antennas fixedly the time, the decoding complex degree of space-time trellis codes (trellis state by decoder is measured several times) increases with transmission rate exponentially level.In view of this, Alamouti has proposed a kind of simple two antennas transmit diversity schemes, and has provided comparatively simple decoding algorithm.People such as Tarkh are therefrom inspired, and use orthogon theory, and this scheme is generalized to the transmit diversity systems with any number of transmit antennas, have proposed Space-Time Block Coding thus.Space-Time Block Coding is compared with space-time trellis codes, though performance decreases, decoding complex degree is greatly diminished.
Hierarchical space-time code is that the information source data are divided into several parallel sub data flows, and the technology that they are encoded independently and modulate is not so it is based on transmit diversity.People such as the Foschini of Bell Laboratory have at first proposed a kind of diagonal angle hierarchical space-time code (Diagonal Bell Labs Layered Space Time Code, be called for short D-BLAST), emission information is carried out Space Time Coding according to diagonal, under Rayleigh fading environment independently, this structure has obtained huge theoretical capacity, its capacity is with the number linear growth of transmitting antenna, can reach 90% shannon capacity, though D-BLAST has preferably characteristic and hierarchical structure when empty, but its defective is exactly that complexity is too high, the practical application difficulty.Empty time-code of horizontal slice (Horizontal BLAST is called for short H-BLAST) and vertical layered space-time code (VerticalBLAST is called for short V-BLAST) have been proposed subsequently.Though the decoding of H-BLAST is simple, characteristic is poor during its sky; And the better performances of V-BLAST, decoding complexity is also little, therefore is used widely.System based on the V-BLAST structure has carried out experimental verification in the laboratory, under the environment of indoor slow fading, the spectrum efficiency of this system is up to 40bit/s/Hz.
There is the signal decoding algorithm of numerous maturations based on the MIMO communication means of V-BLAST structure, as maximum likelihood algorithm, zero forcing algorithm, least-mean-square error algorithm etc.Be example with ZF (Zero-Forcing is called for short ZF) algorithm below, introduce MIMO signal detection algorithm based on the V-BLAST structure.
As shown in Figure 2, the emission data 141 of transmitting terminal are by V-BLAST coding 151, become parallel M circuit-switched data symbols streams to launch the emission digital coding from antenna 111, through after the wireless channel, received simultaneously by N reception antenna 112 at receiving terminal, and the signal that receives is carried out V-BLAST decode 152, such as adopting ZF to detect, will launch data at last and recover 142.
Equivalent base band transmit M n dimensional vector n is defined as a=(a 1a 2A M) T, a kThe data of representing k transmitting antenna, corresponding received signal vector is r=(r 1r 2R N) T, can be expressed as
r＝Ha+N (1)
Wherein
Figure A20061003573100071
h I, jThe channel fading factor of expression from j transmitting antenna to i reception antenna supposed different h I, jBetween separate, N represents the Gaussian noise vector of receiving terminal.
Be expressed as follows by the ZF detection method of directly inverting, the estimated value  of the vector that transmits is
＝a+H N (2)
Wherein, () The pseudoinverse of representing matrix (Moore-Penrose is called for short MP).The principle of this method is directly to the channel matrix operation of inverting, and the signal phasor that receives with this inverse matrix premultiplication is deciphered each component more simultaneously then, and the advantage of this method is simple, and complexity is low, and shortcoming is that the decoding effect is relatively poor.
The characteristics of distributing antenna system and mimo system are combined, formed the distributed MIMO system.The distributed MIMO system has merged the advantage of distributing antenna system and MIMO technology, can effectively reduce the power requirement to transmitting, and improves cell coverage, reaches good spectrum efficiency, higher system capacity and communication quality preferably.
Have now the distributed MIMO Study on Technology is mainly contained the channel model of distributed MIMO, the channel capacity of distributed MIMO system, the availability of frequency spectrum and the distributed MIMO coherent detection algorithm of distributed MIMO.In the down link of distributed MIMO system, because transmitting antenna is distributed in diverse geographic location, different transmit antennas is unequal to reception antenna dissemination channel time delay, caused can not arriving reception antenna simultaneously from the signal of different antennae emission, therefore traditional MIMO detection technique is no longer suitable.Roll up the 1st phase the 135th～138 page (hereinafter to be referred as document one) at " electronics and the information journal " the 28th that publish in January, 2006, proposed a kind of distributed MIMO coherent detection algorithm, solved this problem effectively based on the V-BLAST structure.
As shown in Figure 3, as follows based on the concrete technical scheme of the distributed MIMO coherent detection algorithm of V-BLAST structure:
Suppose that each transmitting antenna 113 once launches S data symbol altogether, the emission data b is by distributed MIMO coding module 161 with after adding protection interval module 170, transmitting as shown in Figure 4 on M antenna.Wherein, the equivalence of the low pass on transmitting antenna k complex baseband signal can be expressed as:
s k ( t ) = E s M Σ i = 1 S - 1 b k ( i ) g ( t - iT s ) , k = 1 , · · · , M . . . ( 3 )
B wherein k(i) be the symbol of emission in i symbol duration of k transmitting antenna, b k ( i ) = 0 , i ∉ { 0,1 , · · · , S - 1 } ; E sBe symbol power, be without loss of generality that establish transmitting antenna here and adopt average power allocation, then the transmitting power of each transmitting antenna is
Figure A20061003573100083
T sBe the data symbol cycle; G (t) is the equivalent complex radical band waveform of transmitting antenna, is without loss of generality, and establishes g (t) here and satisfies: g (t)=0, and t ≠ [0, T s); | | g ( t ) | | 2 = ∫ 0 T s g ( t ) g * ( t ) dt = 1 , Wherein subscript * represents complex conjugate.
Document one is to adopt single footpath rayleigh fading channel, and the hypothesis channel condition information is known at receiving terminal.So the signal on j reception antenna of receiving terminal can be expressed as
r j ( t ) = Σ k = 1 M h j , k ( i ) s k ( t - τ k ) + n j ( t ) . . . ( 4 )
H wherein J, k(i), be that transmitting antenna k is to the complex channel fading factor of reception antenna j during i the emission symbol.τ kRepresent transmitting of k transmitting antenna, and satisfy 0≤τ through the dissemination channel time delay of arrival receiving terminal behind the wireless channel k＜T sBe without loss of generality, transmitting antenna arranged made 0≤τ 1＜τ 2＜...＜τ M＜T sn j(t) be j the additivity white complex gaussian noise on the reception antenna, its average is zero, and variance is σ j 2
As shown in Figure 5, the signal r on j reception antenna 114 j(t) received by j sub-receiving terminal 190: at first by matched filter banks the signal that different transmit antennas arrives reception antenna j is carried out matched filtering, this matched filter banks comprises M matched filter.Received signal by the matched filter of transmitting antenna m after l constantly be output as
y j m ( l ) = ∫ lT s + τ m ( l + 1 ) T s + τ m r j ( t ) g * ( t - l T s - τ m ) dt . . . ( 5 )
Bring formula (3) and formula (4) into formula (5)
y j m ( l ) = E s M Σ i = 0 S - 1 Σ k = 1 M ∫ l T s + τ m ( l + 1 ) T s + τ m b k ( i ) h j , k ( i ) g ( t - iT s - τ k ) g * ( t - lT - τ m ) dt
+ ∫ lT s + τ m ( l + 1 ) T s + τ m n j ( t ) g * ( t - lT s - τ m ) dt (6)
Suppose
R m , k ( l - i ) = ∫ l T s + τ m ( l + 1 ) T s + τ m g ( t - iT s - τ k ) g * ( t - lT s - τ m ) dt . . . ( 7 )
n j m ( l ) = ∫ lT s + τ m ( l + 1 ) T s + τ m n j ( t ) g * ( t - lT s - τ m ) dt . . . ( 8 )
Then formula (8) but abbreviation be
y j m ( l ) = E s M Σ i = 0 S - 1 Σ k = 1 M R m , k ( l - i ) h j , k ( i ) b k ( i ) + n j m ( l ) . . . ( 9 )
Introduce the channel correlation matrix R (l-i) of M * M, its element is R M, k(l-i).R (l-i) satisfies R (l-i)=R H(i-l), wherein () HThe expression complex-conjugate transpose.By g (t) satisfied condition and 0≤τ 1＜τ 2＜...＜τ M＜T sCan get
R(l-i)＝0，|l-i|＞1 (10)
If j reception antenna is h at the diagonal angle channel matrix of the corresponding time slot of l symbol j(l)=diag{h J, 1(l), h J, 2(l) ..., h J, M(l) }, j reception antenna matched filter banks be at l=0, and 1 ..., S-1 output type (9) constantly can be expressed as vector form
y j ( l ) = E s M Σ i = 0 S - 1 R ( l - i ) h j ( i ) b ( i ) + n j ( l ) . . . ( 11 )
y j ( l ) = ( y j 1 ( l ) , y j 2 ( l ) , · · · , y j M ( l ) ) T , b ( i ) = ( b 1 ( i ) , b 2 ( i ) , · · · , b M ( i ) ) T , n j ( l ) = ( n j 1 ( l ) , n j 2 , · · · , n j M ( l ) ) T .
From formula (11) as can be seen, because the influence of the dissemination channel time delay of distributed MIMO, the signal of emission has been subjected to the interference that other time slots of part transmit simultaneously in l symbol time slot of transmitting antenna.This is distributed MIMO and the most basic difference of traditional MIMO, and these characteristics have determined that the signal detection theory of traditional MIMO is no longer suitable in distributed MIMO.
Following wushu (11) is expressed as more succinct matrix form.Definition time delay correlation matrix And channel matrix H j:
Figure A20061003573100102
H j＝diag{h j(0)，h j(1)，…，h j(S-1)} (13)
Wherein, Be the piece symmetry Toeplitz matrix of SM * SM, H jIt is SM * SM diagonal matrix.If Y j = ( y j T ( 0 ) , y j T ( 1 ) , · · · , y j T ( S - 1 ) ) T , b = ( b T ( 0 ) , b T ( 1 ) , · · · , b T ( S - 1 ) ) T , n j = ( n j T ( 0 ) , n j T ( 1 ) , · · · , n j T ( S - 1 ) ) T Then carry out the signal Y that extracts after the matched filtering at reception antenna j from symbol time slot 0 to S-1 jCan be expressed as:
Based on following formula, the detection algorithm of traditional MIMO such as ZF detect, ordering interference cancellation (OrderedSuccessive Interference Cancellation is called for short OSIC) can be used for the distributed MIMO system.Be example with the ZF detection below, being estimated as of SM symbol of M the transmission antennas transmit that detects from j reception antenna:
Wherein, () -1Represent matrix inversion.Because
Figure A20061003573100109
It is full rank.
Described above is that the receiving terminal of distributed MIMO system is the situation of single antenna.When receiving terminal is many antennas, transmitting of being detected on N reception antenna altogether merged (merging as high specific), can recover the emission symbol more accurately.Based on formula (14), merge into example with high specific:
Y = Σ j = 1 N H j H Y j . . . ( 16 )
Formula (16) is carried out ZF to be detected and can get
Figure A20061003573100111
Adopt ideal communication channel to estimate in the coherent detection algorithm of above-mentioned distributed MIMO system, suppose that the channel fading factor is known at receiving terminal, do not provide the channel estimation methods of distributed MIMO system.
To sum up, existing distributed mimo system coherent detection algorithm all is that the hypothesis channel fading factor is known at receiving terminal, but does not provide distributed MIMO system channel estimation approach.
Summary of the invention
The technical problem that the present invention solves is to disclose a kind of distributed MIMO system and channel estimation methods, with under the rayleigh fading channel condition of single footpath, utilize the auxiliary mutually channel estimating that realizes in distributed multiple-input and multiple-output (MIMO) system of pilot frequency sequence.
For addressing the above problem, the invention discloses a kind of distributed MIMO system, comprise transmitting terminal and receiving terminal, described transmitting terminal comprises distributed multiple-input and multiple-output coding module, be used for will input the emission digital coding be the data flow of multidiameter delay and the output of data segment that every circuit-switched data stream is set to some predetermined lengths, key is that described transmitting terminal also comprises:
The radiating circuit of multidiameter delay, be connected with described distributed multiple-input and multiple-output coding module signal output part respectively, described radiating circuit is used for the circuit-switched data stream work of distributed multiple-input and multiple-output coding module output is inserted pilot frequency sequence, adds protection processing at interval with the composition Frame, and with this Frame radio-frequency transmissions;
Described receiving terminal specifically comprises:
The receiving circuit of multidiameter delay is used to receive the Frame of described transmitting terminal radio-frequency transmissions, and obtains described pilot frequency sequence and described data segment from described Frame;
The frequency pilot sign module is used to export corresponding described radiating circuit way and is the pilot frequency sequence of predetermined length;
Channel estimation module, the pilot frequency sequence that is used for the output of the pilot frequency sequence that obtains according to described receiving circuit and described frequency pilot sign module obtains channel estimate matrix.
Described radiating circuit specifically comprises:
The frequency pilot sign module is used to produce the pilot frequency sequence of predetermined length;
Insert pilot module, be used for the pilot frequency sequence that described frequency pilot sign module produces is inserted into the data segment of described data flow;
Interpolation protection interval module is used for the protection interval to the data segment and the pilot frequency sequence interpolation predetermined length of the described data flow after handling through described insertion pilot module;
Frame forms module, is used for Frame and output are formed in the output of described interpolation protection interval module;
Transmitting antenna transmits wired media by signal and links to each other with described frame formation module, is used for described Frame is launched through after the radio frequency processing.
Described protection predetermined length at interval is the length of the maximum channel propagation delay in this distributed MIMO system channel.
Described receiving terminal also comprises:
Distributed multiple-input and multiple-output decoder module is used for obtaining from the data segment of described receiving circuit according to described channel estimate matrix the estimated value of described emission data.
Described receiving circuit specifically comprises:
Reception antenna is used to receive the described Frame that described transmitting terminal is launched;
Extract pilot module, transmit wired media by signal and link to each other, be used for extracting pilot frequency sequence and data segment from described Frame with described reception antenna.
Correspondingly, the present invention also discloses a kind of channel estimation methods of distributed MIMO system, and key is to comprise:
Emission digital coding step: will launch the data flow that digital coding is a multidiameter delay by distributed multiple-input and multiple-output coding, and every circuit-switched data stream is set to the data segment output of some predetermined lengths;
Data transmission step: the parallel duplex data flow that the emission data form is inserted pilot frequency sequence respectively, formed Frame and radio-frequency transmissions output after adding protection processing at interval;
Data Receiving step: receive the Frame of described data transmission step emission, and therefrom obtain pilot frequency sequence and data segment;
Channel estimation steps: the pilot frequency sequence according to pilot frequency sequence that obtains in the described Data Receiving step and the output of described frequency pilot sign module obtains channel estimate matrix.
Described data transmission step comprises:
Insert the pilot frequency sequence step: the data segment that the pilot frequency sequence of predetermined length is inserted into described data flow;
The interpolation protection is step at interval: with the protection interval through data segment in the described data flow after the described insertion pilot frequency sequence step process and pilot frequency sequence interpolation predetermined length;
Frame forms step: will form Frame and output through the described data flow after the step process of described interpolation protection interval;
Wireless transmission step: described Frame radio-frequency transmissions is exported by spaced antenna.
Described Data Receiving step comprises:
Wireless receiving step: the described Frame that receives described data transmission step emission by spaced antenna;
Extract the pilot tone step: from described Frame, obtain pilot frequency sequence and data segment respectively.
Described channel estimation steps is obtained channel estimate matrix for adopting the multi-input multi-ouput channel estimation technique.
The described multi-input multi-ouput channel estimation technique is a least square channel estimating method.
This method also comprises: emission data recovering step: the estimated value of obtaining described emission data according to the data segment of the channel estimate matrix in the described channel estimation steps from described Data Receiving step.
Compared with prior art, the present invention has following beneficial effect:
(1) the invention provides a kind of distributed MIMO system and channel estimation methods, solved the channel estimation problems in the distributed MIMO system effectively;
(2) the present invention is lower to the requirement of pilot frequency sequence number, promptly can finish channel estimating preferably as long as use pilot frequency sequence to surpass one;
The number of the pilot frequency sequence that comprises in (3) Frames and the number of data segment can be regulated according to the actual needs of engineering, few more in the pilot frequency sequence number, under the many more situation of the number of data segment, can improve the data transmission efficiency of this distributed MIMO system;
(4) channel estimation methods of the present invention and existing mimo system has compatible preferably: the least square in the existing mimo channel method of estimation, least mean-square error etc. all can be expanded and be used for the present invention, and the pilot frequency sequence in the existing mimo system also can be used among the present invention.
Description of drawings
Fig. 1 is the spaced antenna schematic diagram.
Fig. 2 adopts the V-BLAST coding techniques to carry out the schematic diagram of radio communication in the mimo system.
Fig. 3 is existing distributed MIMO system schematic.
Fig. 4 is in the system shown in Figure 3, to the composition schematic diagram after the emission data segment interpolation protection at interval.
Fig. 5 is the operation principle schematic diagram of receiving terminal in the system shown in Figure 3.
Fig. 6 is a distributed MIMO system schematic of the present invention.
Fig. 7 is the schematic diagram of the specific embodiment of a Frame of the present invention.
Fig. 8 is the schematic flow sheet of the inventive method.
Embodiment
Please referring to shown in Figure 6, be a kind of distributed multiple-input and multiple-output disclosed in this invention (MIMO) system, this system comprises transmitting terminal and receiving terminal two parts, the emission data b is under the rayleigh fading channel condition of single footpath, utilize the supplementary mode of pilot frequency sequence to export with the Frame radio-frequency transmissions from described transmitting terminal, and described receiving terminal receives described Frame and therefrom obtains described pilot frequency sequence, and according to being inserted into pilot frequency sequence in the described emission data to obtain the channel estimating of this distributed MIMO system.
Described transmitting terminal comprises:
Distributed multiple-input and multiple-output (MIMO) coding module 210, adopt the demixing time space technology (as V-BLAST) in the mimo system, this distributed MIMO coding module 210 is used for the emission data b of input is encoded to the parallel data flow in M (M is a positive integer) road, and is set to the data segment output of some predetermined length S according to the every circuit-switched data stream of prior art (document one);
The radiating circuit 220 of multidiameter delay; be connected with described distributed MIMO coding module 210 signal output parts respectively; described radiating circuit 220 is used for the circuit-switched data stream work of described distributed MIMO coding module 210 outputs is inserted pilot frequency sequence, adds protection processing at interval with the composition Frame, and with this Frame radio-frequency transmissions.
Wherein, described radiating circuit 220 comprises:
Frequency pilot sign module 221 is used to produce the pilot frequency sequence of predetermined length L;
Insert pilot module 222, be used for the pilot frequency sequence that described frequency pilot sign module 221 produces is inserted into the data segment of described data flow;
Interpolation protection interval module 223 is used for the data segment of the described data flow after handling through described insertion pilot module 222 and the protection interval that pilot frequency sequence adds predetermined length;
Frame forms module 224, is used for Frame and output are formed in the output of described interpolation protection interval module 223;
Transmitting antenna 225 transmits wired media by signal and links to each other with described frame formation module 224, is used for described Frame is launched through after the radio frequency processing.
Described protection predetermined length at interval is the maximum channel propagation delay τ in this distributed MIMO system channel MaxLength.
Please, provide the schematic diagram of a kind of embodiment of Frame referring to as Fig. 7.In this schematic diagram, suppose to insert a pilot frequency sequence behind J the data segment, wherein J is determined by the situation of change of channel, guarantees that J data segment and the channel situation that pilot frequency sequence experienced are approximate; Therefore, each Frame comprises J data sign field and a pilot frequency sequence.
Described receiving terminal comprises:
The receiving circuit 230 that N (N is a positive integer) road is parallel is used to receive the Frame of described transmitting terminal radio-frequency transmissions, and obtains described pilot frequency sequence Y from described Frame J, pAnd described data segment;
Frequency pilot sign module 240 is used to export corresponding described radiating circuit 220 ways and is the pilot frequency sequence c of predetermined length L p, also i.e. output is that the length that M the pilot frequency sequence on the transmitting antenna 225 formed is the sequence of L * M;
Channel estimation module 250 is used for the pilot frequency sequence Y that obtains according to described receiving circuit 230 J, pAnd the pilot frequency sequence c of described frequency pilot sign module 240 outputs pObtain channel estimate matrix;
Distributed MIMO decoder module 260 is used for obtaining from the data segment of described receiving circuit 230 according to described channel estimate matrix the estimated value of described emission data.
Wherein, described receiving circuit 230 comprises:
Reception antenna 231 is used to receive the described Frame that described transmitting terminal is launched;
Extract pilot module 232, transmit wired media by signal and link to each other, be used for extracting pilot frequency sequence Y from described Frame with described reception antenna 231 J, pAnd data segment.
Described channel estimation module 250 is according to described pilot frequency sequence Y J, pAnd described pilot frequency sequence c p, can form similar matrix notation as the formula (14):
And described channel estimation module 250 obtains channel estimate matrix for adopting existing mimo system channel estimating method, for example, adopts least square (Least Square is called for short LS) channel estimating method.Below be example with LS channel estimating method, and in conjunction with prior art, the channel matrix that estimates is expressed as follows:
Figure A20061003573100171
The channel matrix that will estimate by above-mentioned channel estimation methods H ^ j ( j = 1,2 , · · · , N ) Input to described distributed multiple-input and multiple-output (MIMO) decoder module 260, then described distributed MIMO decoder module 260 can obtain the estimated value  of described emission data b from the data segment the described receiving circuit 230.
Corresponding, the invention also discloses the channel estimation methods of a kind of distributed multiple-input and multiple-output (MIMO) system, be applied to aforesaid distributed MIMO system, be used for channel estimating to this distributed MIMO system.
Please referring to shown in Figure 8.This method comprises:
Emission digital coding step s310: will launch data b by distributed MIMO coding (as V-BLAST) and be encoded to the parallel data flow in M road, and every circuit-switched data stream is set to the data segment output of some predetermined length S;
Data transmission step: the parallel duplex data flow that the emission data form is inserted pilot frequency sequence respectively, formed Frame and radio-frequency transmissions output after adding protection processing at interval;
Described data transmission step specifically comprises:
Insert pilot frequency sequence step s320: the data segment that the pilot frequency sequence of predetermined length L is inserted into described data flow;
Add protection step s330 at interval: the protection that data segment in the described data flow after the described insertion pilot frequency sequence step s320 of process is handled and pilot frequency sequence add predetermined length at interval;
Frame forms step s340: the described data flow after step s330 handles at interval through described interpolation protection is formed Frame and output;
Wireless transmission step s350: described Frame radio-frequency transmissions is exported by spaced antenna.
Data Receiving step: receive the Frame of described data transmission step emission, and therefrom obtain pilot frequency sequence and data segment;
Described Data Receiving step specifically comprises:
Wireless receiving step s360: the described Frame that receives described data transmission step emission by spaced antenna;
Extract pilot tone step s370: from described Frame, obtain pilot frequency sequence and data segment respectively.
Channel estimation steps s380: according to the pilot frequency sequence Y that obtains in the described Data Receiving step J, pAnd the pilot frequency sequence c of described frequency pilot sign module 240 outputs pObtain channel estimate matrix H ^ j ( j = 1,2 , · · · , N ) (shown in the formula of stating of seing before (19)).
Wherein, described channel estimation steps s380 obtains channel estimate matrix for adopting existing mimo system channel estimating method, such as being least square channel estimating method.
In addition, in the present invention, also comprise emission data recovering step, obtain the estimated value of described emission data according to the data segment of the channel estimate matrix in the described channel estimation steps from described Data Receiving step.That is: the channel matrix that will estimate by above-mentioned channel estimation methods H ^ j ( j = 1,2 , · · · , N ) Input to described distributed MIMO decoder module 260, then described distributed MIMO decoder module 260 can obtain the estimated value  of described emission data b from the data segment the described receiving circuit 230.
Among the present invention, it is optical fiber or cable that the described signal that is used to connect described transmitting antenna 225 and described reception antenna 231 transmits wired media.And the channel estimation methods of existing mimo system all can be expanded such as channel estimation methods such as least square, least mean-square errors and to be used for distributed MIMO system channel of the present invention and to estimate; Pilot frequency sequence in the existing mimo system also can be used in the channel estimating of distributed MIMO of the present invention system.
To sum up, a kind of distributed MIMO system provided by the invention and channel estimation methods have solved the channel estimation problems in the distributed MIMO system effectively, and compared with prior art, this invention has following beneficial effect:
(1) the present invention is lower to the requirement of pilot frequency sequence number, promptly can finish channel estimating preferably as long as use pilot frequency sequence to surpass one;
The number of the pilot frequency sequence that comprises in (2) Frames and the number of data segment can be regulated according to the actual needs of engineering, few more in the pilot frequency sequence number, under the many more situation of the number of data segment, can improve the data transmission efficiency of this distributed MIMO system;
(3) channel estimation methods of the present invention and existing mimo system has compatible preferably: the least square in the existing mimo channel method of estimation, least mean-square error etc. all can be expanded and be used for the present invention, and the pilot frequency sequence in the existing mimo system also can be used among the present invention.
Above embodiment only in order to the explanation the present invention and and unrestricted technical scheme described in the invention; Therefore, although this specification has been described in detail the present invention with reference to each above-mentioned embodiment,, those of ordinary skill in the art should be appreciated that still and can make amendment or be equal to replacement the present invention; And all do not break away from the technical scheme and the improvement thereof of the spirit and scope of the present invention, and it all should be encompassed in the middle of the claim scope of the present invention.

Claims (12)

1. distributed MIMO system, comprise transmitting terminal and receiving terminal, described transmitting terminal comprises distributed multiple-input and multiple-output coding module, be used for will input the emission digital coding be the data flow of multidiameter delay and the output of data segment that every circuit-switched data stream is set to some predetermined lengths, it is characterized in that described transmitting terminal also comprises:
The radiating circuit of multidiameter delay, be connected with described distributed multiple-input and multiple-output coding module signal output part respectively, described radiating circuit is used for the circuit-switched data stream work of distributed multiple-input and multiple-output coding module output is inserted pilot frequency sequence, adds protection processing at interval with the composition Frame, and with this Frame radio-frequency transmissions;
Described receiving terminal comprises:
The receiving circuit of multidiameter delay is used to receive the Frame of described transmitting terminal radio-frequency transmissions, and obtains described pilot frequency sequence and described data segment from described Frame;
The frequency pilot sign module is used to export corresponding described radiating circuit way and is the pilot frequency sequence of predetermined length;
Channel estimation module, the pilot frequency sequence that is used for the output of the pilot frequency sequence that obtains according to described receiving circuit and described frequency pilot sign module obtains channel estimate matrix.
2. distributed MIMO system according to claim 1 is characterized in that, described radiating circuit specifically comprises:
The frequency pilot sign module is used to produce the pilot frequency sequence of predetermined length;
Insert pilot module, be used for the pilot frequency sequence that described frequency pilot sign module produces is inserted into the data segment of described data flow;
Interpolation protection interval module is used for the protection interval to the data segment and the pilot frequency sequence interpolation predetermined length of the described data flow after handling through described insertion pilot module;
Frame forms module, is used for Frame and output are formed in the output of described interpolation protection interval module;
Transmitting antenna transmits wired media by signal and links to each other with described frame formation module, is used for described Frame is launched through after the radio frequency processing.
3. distributed MIMO system according to claim 2 is characterized in that, described protection predetermined length at interval is the length of the maximum channel propagation delay in this distributed MIMO system channel.
4. distributed MIMO system according to claim 1 is characterized in that, described receiving terminal also comprises:
Distributed multiple-input and multiple-output decoder module is used for obtaining from the data segment of described receiving circuit according to described channel estimate matrix the estimated value of described emission data.
5. distributed MIMO system according to claim 4 is characterized in that, described receiving circuit specifically comprises:
Reception antenna is used to receive the described Frame that described transmitting terminal is launched;
Extract pilot module, transmit wired media by signal and link to each other, be used for extracting pilot frequency sequence and data segment from described Frame with described reception antenna.
6. a channel estimation methods is characterized in that, comprising:
Data transmission step: the parallel duplex data flow that the emission data form is inserted pilot frequency sequence respectively, formed Frame and radio-frequency transmissions output after adding protection processing at interval;
Data Receiving step: receive the Frame of described data transmission step emission, and therefrom obtain pilot frequency sequence and data segment;
Channel estimation steps: the pilot frequency sequence according to pilot frequency sequence that obtains in the described Data Receiving step and the output of described frequency pilot sign module obtains channel estimate matrix.
7. channel estimation methods according to claim 6 is characterized in that, described data transmission step also comprises:
Emission digital coding step: will launch the data flow that digital coding is a multidiameter delay by distributed multiple-input and multiple-output coding, and every circuit-switched data stream is set to the data segment output of some predetermined lengths.
8. channel estimation methods according to claim 7 is characterized in that, described data transmission step comprises:
Insert the pilot frequency sequence step: the data segment that the pilot frequency sequence of predetermined length is inserted into described data flow;
The interpolation protection is step at interval: with the protection interval through data segment in the described data flow after the described insertion pilot frequency sequence step process and pilot frequency sequence interpolation predetermined length;
Frame forms step: will form Frame and output through the described data flow after the step process of described interpolation protection interval;
Wireless transmission step: described Frame radio-frequency transmissions is exported by spaced antenna.
9. channel estimation methods according to claim 6 is characterized in that, described Data Receiving step comprises:
Wireless receiving step: the described Frame that receives described data transmission step emission by spaced antenna;
Extract the pilot tone step: from described Frame, obtain pilot frequency sequence and data segment respectively.
10. channel estimation methods according to claim 6 is characterized in that, described channel estimation steps is obtained channel estimate matrix for adopting the multi-input multi-ouput channel estimation technique.
11. channel estimation methods according to claim 10 is characterized in that, the described multi-input multi-ouput channel estimation technique is a least square channel estimating method.
12. according to each described channel estimation methods of claim 6 to 11, it is characterized in that, also comprise:
Emission data recovering step: the estimated value of obtaining described emission data according to the data segment of the channel estimate matrix in the described channel estimation steps from described Data Receiving step.
CN 200610035731 2006-05-31 2006-05-31 Distributed MIMO system and channel estimation method Pending CN1968241A (en)

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CN102377699A (en) * 2010-08-16 2012-03-14 中兴通讯股份有限公司 Channel estimation method and device for multi-user multi-input multi-output (MU-MIMO) system
CN101394216B (en) * 2007-09-18 2013-01-16 中兴通讯股份有限公司 Pre-coding method and codebook constructing method based on code book mode
CN102959916A (en) * 2010-06-11 2013-03-06 阿尔卡特朗讯 Mimo transmission system with decentralized channel estimation and precoding
CN101772913B (en) * 2007-08-02 2013-07-03 富士通株式会社 Pilot arrangement method in a mobile radio communication system and transmitter receiver set applied in the method
WO2015158003A1 (en) * 2014-04-18 2015-10-22 华为技术有限公司 Pilot sending method, channel estimation method and apparatuses
CN105933049A (en) * 2007-06-11 2016-09-07 皇家飞利浦电子股份有限公司 A method, a transmitting station and a receiving station for analog beam forming
CN106211042A (en) * 2016-07-12 2016-12-07 东南大学 A kind of signal detecting method of the M2M system for distributed antenna architecture

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105933049A (en) * 2007-06-11 2016-09-07 皇家飞利浦电子股份有限公司 A method, a transmitting station and a receiving station for analog beam forming
CN101772913B (en) * 2007-08-02 2013-07-03 富士通株式会社 Pilot arrangement method in a mobile radio communication system and transmitter receiver set applied in the method
CN101394216B (en) * 2007-09-18 2013-01-16 中兴通讯股份有限公司 Pre-coding method and codebook constructing method based on code book mode
CN102959916A (en) * 2010-06-11 2013-03-06 阿尔卡特朗讯 Mimo transmission system with decentralized channel estimation and precoding
CN102959916B (en) * 2010-06-11 2015-11-25 阿尔卡特朗讯 There is the mimo transmission system of distributed channel estimation and precoding
CN102377699A (en) * 2010-08-16 2012-03-14 中兴通讯股份有限公司 Channel estimation method and device for multi-user multi-input multi-output (MU-MIMO) system
CN102377699B (en) * 2010-08-16 2014-11-05 中兴通讯股份有限公司 Channel estimation method and device for multi-user multi-input multi-output (MU-MIMO) system
WO2015158003A1 (en) * 2014-04-18 2015-10-22 华为技术有限公司 Pilot sending method, channel estimation method and apparatuses
CN106211042A (en) * 2016-07-12 2016-12-07 东南大学 A kind of signal detecting method of the M2M system for distributed antenna architecture
CN106211042B (en) * 2016-07-12 2019-03-12 东南大学 A kind of signal detecting method of the M2M system for distributed antenna architecture

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